The Electronic Structure And Optical Properties Of SnO₂ Nanomaterials

As a excellent transparent conductive material and a typical braod bandgap semiconductor with band gap is 3.6eV, Tin dioxide(SnO2) has great potential for development in the semiconductor industry. The low demension intrinsic and doped SnO2 materials have most of excellent properties,such as the high light transmittance,good electrical conductivity,the strong ultraviolet absorption ability and so on.These excellent properties have broadened the application value of SnO2 in the photoelectric field. In our works, Based on the SnO2 namomaterials, All the calculations were carried out using the Vienna ab initio simulation package(VASP) and Wien2 k based on density-functional theory(DFT) with the projector augmented wave(PAW) method. Generalized gradient approximation(GGA) with the Perdew Burke Ernzerhof(PBE) exchange-correlation functional was adopted to describe the exchange correlation interaction.Firstly, We calculated the electronic structures, energy band straucture and optical properties of intrinsic bulk SnO2 and Zr-doped and Zr、N co-doped SnO2 materials. The results shown that when introduced Zr and N atoms,the SnO2 has a smaller gap that pristine and enhanced conducivity. The calculation of optical properties shown that the absorb edge shift to low energy rigion when introducing Zr and N atoms and the optical absorption capacity was also significantly increased.Base on the bulk SnO2 materials, we constructed the two dimensional SnO2 monolayer. We calcalated the electronic structure and optical properties using the first principle. The conclusions shown that the SnO2 monolayer has the direct band gap with the band gap of SnO2 is 2.78 eV which is lager than the band gap of bulk SnO2 model. When introducing Ag atoms, the SnO2 monolayer has the smaller gap and the stronger electrical conductivity than intrinsic SnO2 monolayer.More interestingly, the doped models possess different optical absorption capacity as different concentration of Ag doped.Then we constructed the armchair and zigzag edge one dimension SnO2 nanoribbons and calculated the vary of band gaps as increasing of the ribbon width. The results shown that both zigzag and armchair SnO2 are indirect bandgap semiconductor and the value of band gap presents obvious with different ribbon width and eventually tend to a certain value. When introducing Ag impurities, the electrical conductivity enhance obviously, and the Ag-doped SnO2 nanoribbons have stronger optical absorption capacity than intrinsic SnO2 nanoribbons.In the end, We studied that electronic structure and bandgap modulations of SnO2 nanoribbon by transverse electricfields and hydrogen passivations,The results shown that the band gap of both Z-SnO2 NRs and A-SnO2 NRs can be reduced monotonically with increasing transverse field strength, demonstrating a gaint Stark effect and the A-SnO2 NRs has a more intense critical field than Z-SnO2 NRs. On the other hand, the Z-SnO2 NRs with the edges fully passiviated(Z-SnO2NRs-2H) and A-SnO2 NRs with only the edge O atoms are passivated(A-SnO2NRs-OH) shows a different band gaps and a slightly weaker Stark effect. Interestingly, the Z-SnO2 NRs emerged the convert of metal-semiconductor-metal under external transverse electronic fields. In the end, we studied the electronic transport properties of the different edges SnO2 NRs. These findings suggest potential ways of band engineering and application in semiconductor industry.